OK, let's do this. We've got 3842 and 1003 and we're adding them all together.

Step 1: We'll start by adding the digits 2 & 3 in column 1 and get 5.

Step 2: We'll start by adding the digits 4 & 0 in column 2 and get 4.

Step 3: We'll start by adding the digits 8 & 0 in column 3 and get 8.

Step 4: We'll start by adding the digits 3 & 1 in column 4 and get 4.

So, 3842 + 1003 = 4845.

